Food mixer

ABSTRACT

A food mixer  10  having a turn table  22  that receives a bowl  23 . Projecting into a bowl  23  are beaters  24  that are driven by means of a motor  13 . The turn table  22  is driven by means of a motor  25 . A common speed control member in the form of a dial  29  operates a pair of potentiometers  31  that control the motors  13  and  25  so that there is a correlation between the speeds thereof.

TECHNICAL FIELD

[0001] The present invention relates to food mixers.

BACKGROUND OF THE INVENTION

[0002] The invention relates to mixers typically used for mixing cakeingredients Such mixers conventionally have a pair of counter-rotatingbeaters which extend downwardly from a mixing head into a mixing bowl.The beaters are offset from the vertical centre axis of the bowl suchthat upon rotation of the bowl, all of the cake ingredients are blendedby the beaters.

[0003] Such food mixers include a base having a turntable or carouselupon which the mixing bowl sits. From the base there extends a post uponwhich there is pivotally mounted a mixing head from which the beatersdepend. A powerful electric motor situated within the head is connectedby transmission means to the beaters. In some machines, torque outputfrom this motor is also transferred via a mechanical transmission to thebase so as to effect rotation of the turntable or carousel. In lessexpensive machines, the turntable rotates as a result of the interactionof the beaters with the ingredients in the bowl. There is a significantloss of the motor's torque in the mechanical transmission from the motorto the base and turntable. For this reason, it is necessary to use anexpensive motor having a torque output not only sufficient to drive thebeaters through the cake ingredients but also to overcome mechanicallosses in transmission to the turntable.

[0004] Also known are hand-held mixers having a pair of counter-rotatingbeaters depending therefrom. Such devices can be used conveniently byholding the device over a mixing bowl, saucepan or other vessel andmanoeuvring the device such that the motor-driven beaters are movedmanually about the vessel for thorough mixing. Some such hand-helddevice can also be used in conjunction with a base having a rotatableturntable upon, which a bowl sits. Such devices have an auxiliary outputshaft from the motor four coupling to a transmission mechanism in thebase to effect rotation of the turntable. These mixers suffer from thesame problems as those fixed-head mixers discussed above.

OBJECT OF THE INVENTION

[0005] It is an object of the present invention to overcome orsubstantially ameliorate at least one of the above disadvantages.

DISCLOSURE OF THE INVENTION

[0006] There is disclosed herein, a food mixer having:

[0007] a base;

[0008] a rotatable member mounted on the base and adapted to receive andsupport a bowl to be rotated by the member;

[0009] a first motor drivingly connected to said rotatable member andlocated within the base and operable to drive the member;

[0010] a bead fixed to the base;

[0011] at least one beater connector supported by said head andconfigured to receive and rotate a beater to extend into the bowl; and

[0012] a second motor drivingly connected to the connector and locatedwithin said head to cause rotation of each connector;

[0013] Preferably said head is affixed to said base so as to pivot abouta horizontal axis.

[0014] Preferably said mixer includes a control circuit electricallyconnected to said first and second motors to ensure a correlationbetween an operating rotational speed of each motor.

[0015] Preferably the control circuit includes two speed controls, onefor adjusting an operational rotational speed of the connector and theother for changing a correlation between the operation rotational speedof the connector and an operational notational speed of said rotatablemember.

[0016] In an alternative preferred form the food mixer further includesa user manipulated member that is moved by the user to control the speedof the first and second motors so that there is a correlation betweenthe speed of a first motor and the speed of a second motor.

[0017] Preferably the food mixer includes a pair of variable resistancepotentiometers operated by said user manipulated member, eachpotentiometer being associated with a respective one of said motors soas to governor the speed thereof.

[0018] Preferably, the user manipulated member is a dial that is movedangularly to cause operation of the potentiometers,

[0019] There is further disclosed herein a food mixer having;

[0020] a base;

[0021] a rotatable member mounted on the base and adapted to receive andsupport a bowl to be rotated by the member;

[0022] a first motor drivingly connected to said rotatable member andlocated within the base and operable to drive the member;

[0023] a head mounted on the base;

[0024] at least one beater connector supported by said head andconfigured to receive and rotate a beater to extend into the bowl;

[0025] a second motor drivingly connected to the connector and locatedwithin said head to cause rotation of each connector;

[0026] a user manipulated member that is moved by a user to govern thespeed of the first and second motors to ensure there is a correlationbetween the speed of the first motor and the speed of the second motor;and

[0027] an electric circuit operated by said user manipulated member todeliver electric power to the first motor and the second motor.

[0028] Preferably the electric circuit includes a pair of variableresistance potentiometers operated by said user manipulated member, eachpotentiometer being associated with a respective one of said electricmotors to control the speed thereof.

[0029] Preferably the user manipulated member is a dial that is movedangularly to cause movement of the potentiometers. mixer; and

[0030]FIG. 3 is a schematic electrical circuits used in the food mixerof FIG. 2.

[0031] Mounted to the head 12 is an electric control circuit 19including a beater speed control dial 17 and a bowl speed control dial18. Both Dials 17 and 18 are moved angularly about the axis 33 tocontrol the speed of the motors 13 and 25.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Preferred forms of the present invention will now be described byway of example with reference to the accompanying drawings wherein:

[0033]FIG. 1 is a schematic cross-sectional elevational view of a firstfood mixer;

[0034]FIG. 2 is a schematic cross-sectional elevational view of a secondfood mixer;

[0035] and

[0036]FIG. 3 is a schematic electrical circuits used in the food mixerof FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] In FIG. 1 of the accompanying drawings where is schematicallydepicted a food mixer 10 having a base 11 to sit upon a bench top and ahead 12 attached hingedly at 24 to base 11 but not removable therefromin general use. The base 11 has a lower portion 38 that rests on akitchen bench, and an upwardly extending item 39 that engages the head12.

[0038] Within the head 12 there is situated a beater motor 13 whichdrives a pair of beaters 14 via a beater transmission mechanism 15 andbeater connectors 35. The motor 13 is cooled by air passing through airvents 21 adjacent to a fascia panel 20.

[0039] Extending upwardly from the head 12 is a handle 16 having abeater eject button 19 which ejects the beaters 14 from the beaterconnectors 35 by mechanical means (not shown).

[0040] Mounted to the head 12 is an electric control circuit 19including a beater speed control dial 17 and a bowl speed control dial18. Both Dials 17 and 18 are moved angularly about the axis 37 tocontrol the speed of the motors 13 and 25.

[0041] Within the base 11 there is situated a turntable motor 25 whichturns a motor sprocket 27. The base 11 supports a rotatable member inthe form of a turntable 22 upon which a bowl 23 can sit to receive thebeaters 14. The turntable 22 has attached to it a turntable sprocket 28.A toothed belt 26 passes around sprockets 27 and 28 to transmit torquefrom motor 25 to turntable 22. The beaters 14 are offset from a verticalcentre line (rotational axis) of the turntable 22 such that rotation ofthe turntable 22 and bowl 23 effects thorough mixing of any ingredientsin the bowl 23.

[0042] Included in the circuit 19 and associated with the speed controldials 17 and 18 are variable resistance devices 20 for individuallycontrolling the supply of electric power to the respective motors 13 and25. A pair of electrical conductors 29 extend between the motors.Control circuitry 19 electronically ensures that there is a correlationbetween the speed at which motor 25 operates and the speed at whichmotor 13 operates. Moreover, the bowl speed control dial 18 can be setto one of a number of preselected setting. However, the bowl 23 willonly rotate upon movement of beater speed control dial 17 to one of anumber of speed setting positions. The beater speed control dial 17might gradually increase or decrease the speed of motor 13 and thereforebeaters 14.

[0043] Alternatively, the beater speed control 17 might simply selectone of a number of operable speeds ranging from say zero to twenty.Depending on the setting of bowl speed control 18, the bowl might rotateslowly, quickly or at an intermediate setting with bowl speeds withineither setting being dependent upon the position of beater speed controldial 17 For example, with the bowl speed control dial 18 set to “SLOW”and the beater speed control dial 17 set to its minimum operationalspeed, then the blow will rotate ever slowly. The speed of the bowl canbe increased without increasing the speed of the beaters by moving thebowl speed control dial 18 to either the intermediate or fast settingThe food mixer can therefore be operated with great flexibility rangingfrom very high beater speed with very low bowl speed to very low beaterspeed and very high bowl speed, and various combinations in between.Within any setting of the bowl speed control 18 (except “OFF”), therotational speed of bowl 23 will vary proportionally with any increaseor decrease in the speed of the beaters 14 set by beater speed controldial 17. In other words, the bowl speed control dial 18 effects therelative speed of the bowl 23 with respect to the speed of the beaters14.

[0044] Each dial 17 and 18 moves a respective one of the devices 20.

[0045] Once mixing is completed, the handle 16 can be used to pivot thehead 12 about pivot so as to raise the beaters 14 out of the bowl 23.The beaters 14 can then be ejected by activation of beater eject button19.

[0046] The base 11 and head 12 might typically be diecast metal orplastic mouldings.

[0047] In FIGS. 2 and 3 of the accompanying drawings there isschematically depicted a modification of the food mixer 10 of FIG. 1. Inthis embodiment the same reference numerals have been applied.

[0048] In the embodiment of FIGS. 2 and 3 there is provided a usermanipulated member in the form of a speed control dial 40. The dial 40operates a pair of variable resistance (adjustable) potentiometers 31that control the speed of the motors 13 and 25. Accordingly, the speedof the motors 13 and 25 is governed by the angular displacement of thedial 40 about axis 37. The potentiometers 31 are on a common shaft toensure that there is a colouration between the speed of the motor 25 andthe speed of the motor 13 that is the potentiometers 31 are moved inunison.

[0049] Accordingly, in the above embodiment the dial 40 simultaneouslyoperates two electric components of an electric circuit 30 to controlthe speed of the motors 13 and 25.

[0050] In the embodiment of FIG. 2 the head 12 is pivotally attached tothe base 11 by means of a pivot assembly 22. The pivot assembly 22provides a horizontal axis about which the head pivot 12. Thishorizontal axis is generally normal to the rotational axis of the turntable 22 and the rotational axis of the connectors 35.

[0051] In the above described preferred embodiments the turn table 22 isdriven by means of sprockets 27 and 28, and belt 26. On an alternativedrive system would include a shaft and pinion gear that would mesh witha gear attached to the turn table 22 and a gear driven by the motor 25.

[0052]FIG. 3 is a schematic diagram of the electronic circuit 30 forcontrolling the speed of alternating current (AC) motors M1 and M2 Theelectronic circuit 30 comprises a power supply circuit 32 and two motordrive circuits 34 and 36, as shown in broken outline.

[0053] Referring to the power supply circuit 32, resistors R1, R2 andcapacitor C1 comprise a mains input filter for filtering the AC mainssignal supplied to the motors M1 and M2 via triacs Q3 and Q4,respectively.

[0054] D1 and D2 comprise a half-wave rectifier for conversion of AC todirect current (DC). Prior to rectification, however, the mains inputvoltage is reduced by capacitor C2 and resistor R4. The output voltageof the half-wave rectifier is regulated by zener diode ZD1 to 15V, andsmoothed by capacitor C3. The resulting DC voltage is selectivelyapplied to the drive circuits 34 and 36 by means of power switch SW1.

[0055] The following description is limited to drive circuit 34.However, drive circuit 36 operates in an identical manner and thefollowing description is thus equally applicable to drive circuit 36,save for the different component references and values.

[0056] Drive circuit 34 comprises integrated circuit IC1, whichgenerates trigger pulses to drive triac Q3, and a number of associatedcomponents, Triac Q3 is connected in series with the motor Ml across theAC mains supply. The drive pulses are routed from pin 4 of IC1 viaresistor R8 to the gate of triac Q3. A current synchronization signal isprovided via R7 to pin 1 of IC1.

[0057] Potentiometers VR1-1 and VR2 control the voltage of the inputsignal supplied to pin 11 of IC1, which is in turn used to adjust thephase angle of the triggering pulses produced at pin 4 of IC1.Potentiometer VR1-1 is adjustable by a user, whereas potentiometer VR2is factory presettable. Capacitor C9 filters high frequency signalsresulting from adjustment of potentiometer VR1-1.

[0058] Resistors R11, R12 and capacitors C4, C5 provide negativefeedback to stabilize an input amplifier internal to IC1.

[0059] Connector CON1 provides a means of connection to a hall-effectsensing device (not shown), located on the shaft of motor M1. Thefeedback signal of the hall-effect device is routed to pin 8 of IC1, viapin 2 of connector CON1 and resistor R16. Pins 1 and 3 of connector CON1represent reference ground and power, respectively.

[0060] Motors M1 and M2 correspond to the bowl motor 25 and the beatermotor 13, respectively, of the mixer 10 as shown in FIG. 2. The analogvariable potentiometers VR1-1 and VR2-2 (potentionmeters 31 of FIG. 2)share a common shaft, which is directly connected to speed control dial40. Angular displacement of the speed control dial 40 by a user of themixer 10, varies the speed of motors M1 and M2.

The claims defining the invention are as follows:
 1. A food mixer having: a base; a rotatable member mounted on the base and adapted to receive and support a bowl to be rotated by the member; a first motor drivingly connected to said rotatable member and located within the base and operable to drive the member; a head fixed to the base; at least one beater connector supported by said head and configured to receive and rotate a beater to extend into the bowl; and a second motor drivingly connected to the connector and located within said head to cause rotation of each connector.
 2. The food mixer of claim 1 wherein said head is affixed to said base so as to pivot about a horizontal axis.
 3. The food mixer of claim 1 or 2 wherein said mixer includes a control circuit electrically connected to said first and second motors to ensure a correlation between an operating rotational speed of each motor.
 4. The food mixer of claim wherein the control circuit includes two speed controls, one for adjusting an operational rotational speed of the connector and the other for changing a correlation between the operation rotational speed of the connector and an operational rotational speed of said rotatable member.
 5. The food mixer of claim 1 further including a user manipulated member that is moved by the user to control the speed of the first and second motors so that there is a correlation between the speed of a first motor and the speed of a second motor.
 6. The food mixer of claim 5 further including a pair of variable resistance potentiometers operated by said user manipulated member, each potentiometer being associated with a respective one of said motors so as to governor the speed thereof
 7. The food mixer of claim 6 wherein said user manipulated member is a dial that is moved angularly to cause operation of the potentiometers.
 8. A food mixer having; a base; a rotatable member mounted on the base and adapted to receive and support a bowl to be rotated by the member; a first motor drivingly connected to said rotatable member and located within the base and operable to drive the member; a head mounted on the base; at least one beater connector supported by said head and configured to receive and rotate a beater to extend into the bowl; a second motor drivingly connected to the connector and located within said head to cause rotation of each connector; a user manipulated member that is moved by a user to govern the speed of the first and second motors to ensure there is a correlation between the speed of the first motor and the speed of the second motor; and an electric circuit operated by said user manipulated member to deliver electric power to the first motor and the second motor.
 9. The food mixer of claim 8 wherein said user manipulates member simultaneously operates two components of said circuit to adjust the speed of the motors simultaneously.
 10. The food mixer of claim 8 wherein the two components of said electric circuit is a pair of variable resistance potentiometers operated by said user manipulated member, each potentiometer being associated with a respective one of said electric motors to control the speed thereof.
 11. The food mixer of claim 9 wherein said user manipulated member is a dial that is moved angularly to cause movement of the potentiometers.
 12. A food mixer substantially as hereinbefore described with reference to FIG. 1 or with reference to FIGS. 2 and
 3. 